ARLINGTON -- Right-hander Luke Jackson, who was switched from being a starter to a reliever earlier this season, is being called up to the Major Leagues. He will be looking to make his Major League debut.

The Rangers announced Thursday that Jackson and right-handed pitcher Anthony Bass are being called up from Triple-A Round Rock for Friday's game with the Mariners. Texas sent down right-hander Phil Klein and left-hander Alex Claudio.

Jackson, who was the 45th overall pick in the 2010 Draft, was 2-2 with a 4.05 ERA in 33 games, including five starts, for Round Rock. Jackson, ranked No. 9 among Rangers prospects by MLB.com, had 71 strikeouts in 60 innings while opponents hit .237 off him, including .185 by left-handed hitters. He had a 3.11 ERA and a .187 opponents batting average as a reliever.

"He's been really good out of the 'pen, especially the last couple of weeks," Rangers general manager Jon Daniels said. "He's always had great stuff -- now we have an opportunity to take a look and see if this is the role that sparks him."

Bass has been the Rangers' long reliever for most of the season, with a 4.35 ERA in 26 relief appearances. He has pitched in 51 2/3 innings, the third most by a reliever in the American League. Bass was optioned to Round Rock on July 27 and made two appearances for the Express.

Claudio has a 2.87 ERA in 18 appearances over three tours with Texas, but he has not pitched since being recalled on July 29. Klein had a 6.75 ERA in 11 appearances.

The Rangers also announced that pitcher Wandy Rodriguez has cleared waivers and been released. He is now a free agent.